Packaging the Lambda

Lambda packaging used to mean a .zip file and hope. Today it is a Dockerfile or a Layer plus a buildspec. We ship a buildspec that builds the function, uploads it, and updates the Lambda configuration on every push to main.

lambda/buildspec.yml

yaml

version: 0.2

phases:
  install:
    runtime-versions:
      python: 3.11
  pre_build:
    commands:
      - pip install --target ./vendor -r requirements.txt
  build:
    commands:
      - zip -r function.zip weather_api.py get-data-api.py vendor
      - aws lambda update-function-code --function-name get_api_weather_data_lambda --zip-file fileb://function.zip

CodeBuild handles install, build, and Lambda update. Notice the requirements.txt install into a vendored directory so the deployment package is self-contained.

Secrets and config flow through Lambda environment variables, set via Terraform or the AWS Console. The function reads WEATHER_API_KEY at runtime. Never hardcode credentials in the script. Never commit them to the repo.

For a daily extract, no. Cold start adds about a second to a 90-second invocation. Provisioned concurrency is overkill. Save your reserved capacity dollars for user-facing endpoints where latency matters.

Quiz: Quiz

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